
I... don't see what you mean. If you compare her to her younger self, the proportions are different, both in body and in the face. Isn't she still in her early teens? In that case, it makes sense/is fine if she still looks like a child, since she is one. To me, her proportions make sense with the art style we've seen so far - the artist tends to draw, especially women's eyes, p big. She's not really an exception to that, it seems to perfectly align with how the artist is drawing other female/child characters.

I don't know how to describe it but basically, I didn't have a single issue with a single character before she grew up and now everytime she appears in a panel, something feels terribly wrong so much so that I can no longer suspend my disbelief and immerse myself in the story. The best way I could describe it was "her face being superimposed on her older body" but maybe something else is bothering me in her exact portrayal and I just can't put my finger on it yet. All I know if that the issue is only with her and not a single other character

Maybe you were expecting her age to be different after the timeskip... most of times authors go from 10- kids to 16+ teens.. mainly because at that age the romance part is more acceptable and can begin. So overall we aren't really used to seeing 12-14yo on comics... and irl they are usually like you described, a childish face on a body that's starting to develop... honestly I'd say your discomfort is a good thing because it shows the artist portrayed her age well, neither a teen nor a kid.
Maybe we are just too used with seeing either kids or late teens in comics... and worse, young teens looking like almost adults.. like those series where the teens are all fully grown adults...

Tbf, in my own experience watching kids grow around me, a lot of 16 y/o can look like adults, especially when it comes to women. I know I finished growing before that age, and have been at the same proportions ever since. It's not true for everyone ofc, and even if they look like adults, they are still children - and ofc being an adult does give you a vibe teens wouldn't have, making it easier to tell irl what age a person might be.
I do agree with you, don't get me wrong. It is annoying and worrisome when teens are adultified in fiction, though that doesn't mean we should treat them the same as younger kids.
This reminds me of a big pet peeve I have when it comes to manhwas/mangas/manhuas I see with growing boys/girls - how they ALWAYS make the boys taller than the girls, even if they're the same age. In my own experience, most boys/girls are roughly the same height for the first 8-13 years, and then the girls get taller first bc they tend to hit puberty earlier, and the boys catch up/get taller around their mid-teens. Ofc this isn't the true for everyone, you can have boys that are taller than girls from a young age, but I see it so often it gets a bit irritating considering it's not how I've seen ppl grow. Hell, I was the tallest in my class for a good few years bc I got my growth spurts around age 10, and it took years until a guy surpassed me.

Oh I totally get it... both points... at 16 most girls I knew looked adultlike... and tried to act so too... my problem with teens I guess is same as yours, adultlile bodies paired with childlike faces... especially the girls. Very big eyes and childish voices... tbh I can't even watch anime anymore cuz the childish voices make me cringe so bad I give up...
I also agree very much about the height thing... honestly even in teens most boys weren't that much taller than the girs and comics (mainly romance) are weird about it... like either the guys are a head taller or a head shorter and made fun of... ik is their anesthetic sense but it's weird to me when fl's are 2 heads shorter than ml's all the time...
Now I wonder how they'll portray ml's height compared to Leo...
Leo's portrayal after the time skip bothers me.....the art feels wrong. It's like the mangaka superimposed her toddler face on an older body and it doesn't look right. I initially thought "is this one of those instances where mangakas are great with drawing male characters but not female ones?" (if you're a yaoi fan, you have come across such cases many many times) but I don't think that is the case because other female characters look fine